CD221/IGF1R Fc Chimera Protein, Human

IGF1R (CD221, insulin-like growth factor 1 receptor) is a transmembrane tyrosine kinase receptor composed of disulfide-linked α₂β₂ heterotetrameric subunits. It exhibits substantial structural homology with the insulin receptor and can form functionally active hybrid receptors. Ligand engagement of IGF-1 or IGF-2 to the cysteine-rich extracellular α chains induces conformational changes that trigger trans-autophosphorylation of the intracellular β-chain tyrosine kinase domains, thereby activating downstream PI3K/AKT and RAS/RAF/MEK/ERK signaling pathways to orchestrate cellular proliferation, survival, anti-apoptotic responses, and metabolic adaptation. Clinically, IGF1R overexpression or genomic amplification has been identified in diverse human malignancies, notably non-small cell lung cancer, breast carcinoma, and Ewing sarcoma, where it serves as an independent prognostic indicator and a druggable therapeutic target. Multiple monoclonal antibodies—including figitumumab and ganitumab—have entered clinical development; however, monotherapy has demonstrated limited efficacy, shifting the strategic focus toward rational combination therapies with EGFR inhibitors, cytotoxic agents, or immune checkpoint blockade, coupled with rigorous biomarker-driven patient selection to identify responsive molecular subtypes.